1. Field of the Invention
The present invention generally relates to color inkjet print apparatuses, and particularly relates to a color inkjet print apparatus which can squirt color inks in a plurality of different sequences. The present invention also relates to an image formation controlling apparatus and a color inkjet printing method.
2. Description of the Related Art
Inkjet print apparatuses that employ inkjet heads for formation of images are used in printers, facsimile apparatuses, copier machines, and the like. The inkjet head is provided with a plurality of nozzles for squirting ink droplets and actuator devices such as electromechanical transducers or electro-thermo transducers corresponding to respective nozzles. Such inkjet head is used as a print head to print high-resolution images with high quality at high speed by forcing ink droplets out of the nozzles onto a record medium (on which ink droplets are placed) in response to record signals.
Such inkjet print apparatuses include a carriage-scan-type color inkjet print apparatus. The carriage-scan-type color inkjet print apparatus has a carriage on which a print head is mounted, and the print head includes a plurality of nozzle lines arranged in the main scan direction, with each nozzle line comprised of a plurality of nozzles and extending in the sub-scan direction. These nozzle lines are assigned to respective colors for squirts of respective color inks through each nozzle, thereby printing color images on a record medium.
Such color inkjet print apparatus creates a color image by the mixing of subtractive colors that places color inks at the same place on the record medium. In order to improve print speed, printing is performed on each way the carriage goes and returns. This is referred to as a two-way print method.
When the two-way print method is carried out with a plurality of nozzles for one color being arranged in the sub-scan direction and a plurality of nozzle lines for respective colors being arranged in the main scan direction, the colors are superimposed in a certain sequence as the carriage goes one way, and are superimposed in a reversed sequence as the carriage returns. This results in the appearance of color prints being different depending on the size of nozzles. For example, the nozzle lines of a print head may be arranged in the order of Y (yellow), M (magenta), C (cyan), and K (black) in the main scan direction. On the way the carriage goes, inks are superimposed in the order of Y, M, and C. On the way the carriage returns, inks are superimposed in the order of C, M, and Y. This creates slightly different appearance of colors that are created by the mixing of subtractive colors.
Japanese Patent Application Publication No. 2001-096770 (Patent Document 1) discloses an inkjet print apparatus which has nozzle lines of respective colors arranged in a symmetric order in the scan direction, thereby achieving the same sequence of color superimposition on each way the head goes and returns.
Japanese Patent Application Publication No. 2000-318190 (Patent Document 2) teaches changing the method of color correction between the way the head goes and the way the head returns, thereby preventing the appearance of colors from varying. Here, the method of color correction converts R (red), G (green), and B (blue), which are three primary colors typically obtained as input data, into CMYK colors that are used by the inkjet print apparatus.
Japanese Patent Application Publication No. 11-170574 (Patent Document 3) actively finds merits in the fact that the appearance of colors differs, and teaches achieving high-quality print by setting the order of ink superimposition to any order.
Patent Document 1 and Patent Document 2 recognize nothing but problems in the fact that the appearance of colors varies depending on the order of ink superimposition. They only attempt to eliminate or make less conspicuous the difference of color appearances.
Patent Document 3 only teaches letting a user specify the sequence of color superimposition. Further, since no particular image processing is performed to match a selected sequence of color superimposition, it is difficult to make the most of the merits.